Liquid crystal display device

Abstract

A liquid crystal (LC) display device includes a LC panel and a driving circuit. The LC panel exhibits, in its voltage-transmittance characteristics, an extreme transmittance at a voltage equal to or lower than a lowest gray-level voltage. The driving circuit supplies to the LC panel a predetermined driving voltage overshooting a gray-level voltage corresponding to an input image signal of a current vertical period, according to a combination of an input image signal of an immediately preceding vertical period and the input image signal of the current vertical period.

Description

[0001]This application is a continuation of U.S. patent application Ser. No. 09 / 820,021, filed 28 Mar. 2001, now abandoned entitled LIQUID CRYSTAL DISPLAY DEVICE.BACKGROUND OF THE INVENTION[0002]1. Field of the Invention[0003]The present invention generally relates to a liquid crystal display device (LCD). More particularly, the present invention relates to an LCD preferably used for moving picture display.[0004]2. Description of the Background Art[0005]The LCDs are used for, e.g., personal computers, word processors, amusement equipments, television sets, and the like. Improvement in response characteristics of the LCDs has been studied for high-quality moving picture display.[0006]Japanese Laid-Open Publication No. 4-288589 discloses an LCD having an increased response speed for intermediate-gray-scale display in order to reduce a residual image. In this LCD, an input image signal having its high-band components pre-enhanced is supplied to a liquid crystal display section so that ...

AI Technical Summary

Benefits of technology

[0018]A liquid crystal display device according to a first aspect of the present invention includes: a liquid crystal panel including a liquid crystal layer and an electrode for applying a voltage to the liquid crystal layer; and a driving circuit for supplying a driving voltage to the liquid crystal panel, wherein the liquid crystal panel exhibits, in its voltage-transmittance characteristics, an extreme transmittance at a voltage equal to or lower than a lowest gray-level voltage, and the driving circuit supplies to the liquid crystal panel a predetermined driving voltage overshooting a gray-level voltage corresponding to an input image signal of a current vertical period, according to a combination of an input image signal of an immediately preceding vertical period and the input image signal of the current vertical period. Thus, the object of the present invention, i.e., improved fall response characteristics, is achieved.

[0024]A liquid crystal display device according to a second aspect of the present invention includes: a liquid crystal panel including a plurality of picture-element capacitors arranged in a matrix, and thin film transistors respectively electrically connected to the plurality of picture-element capacitors; and a driving circuit for supplying a driving voltage to the liquid crystal panel, wherein the liquid crystal display device updates display every vertical period by rendering the plurality of picture-element capacitors in a charged state corresponding to the input image signal, each of the plurality of picture-element capacitors includes a liquid crystal capacitor formed from a corresponding picture-element electrode, a counter electrode and a liquid crystal layer provided between the picture-element electrode and the counter electrode, and a storage capacitor electrically connected in parallel with the liquid crystal capacitor, a capacitance ratio of the storage capacitor to the liquid crystal capacitor being 1 or more, and the picture-element capacitor retains 90% or more of a charging voltage over a single vertical period, when at least a highest gray-level voltage is applied. Thus, the object of the present invention, i.e., improved response characteristics at least at a high-band level, is achieved.

Problems solved by technology

However, the effect of improving the response characteristics at a fall (a change to the display state corresponding to a decrease in voltage applied to the liquid crystal layer) is relatively poor.

Therefore, the effect of increasing the fall response speed is poor even if the input image signal S(t) is emphasized.

Moreover, the driving method disclosed in the aforementioned Japanese Laid-Open Publication No. 4-288589 has a problem that the input image signal S(t) capable of being subjected to effective high-band enhancement is limited.

However, if the high-band correction signal Sc(t)>the high-band limit signal, a correction signal enough to cause a sufficient change in transmittance cannot be input to the liquid crystal display section.

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